title: Long-term stimulation of areca nut components results in increased chemoresistance through elevated autophagic activity.
abstract: BACKGROUND
  We previously demonstrated the autophagy-inducing activity in the crude extract of areca nut (ANE) and its 30-100 kDa fraction (ANE 30-100 K). This study aimed to analyze whether chronic ANE and ANE 30-100 K stimulations lead to higher stress resistance and autophagic activity in oral cells, and whether the resulting autophagic status in stimulated cells correlates with stress resistance.
  
  
  METHODS
  Malignant cells from the mouth oral epidermoid carcinoma Meng-1 (OECM-1) and blood (Jurkat T) origins were stimulated with non-cytotoxic ANE and ANE 30-100 K for 3 months. Sensitivity to anticancer drugs of and autophagy status in stimulated cells, analyzed respectively by XTT assay and calculating microtubule-associated protein 1 light chain 3-II LC3-II/β-actin ratios from Western blot, were compared to non-treated cells. Autophagy inhibitors, 3-methyladenine (3-MA) and chloroquine (CQ), were used to assess whether autophagy inhibition interferes the altered chemoresistance.
  
  
  RESULTS
  Areca nut extract-stimulated (ANE-s) and ANE 30-100 K-stimulated (30-100 K-s) OECM-1 and Jurkat T cells generally exhibited higher cisplatin and 5-fluorouracil (5-FU) resistances, compared to non-stimulated cells. Most stimulated cells expressed significantly higher levels of LC3-II and Atg4B proteins. Interestingly, these cells also showed stronger tolerances against hypoxia environment and expressed higher LC3-II levels under glucose-deprived and hypoxia conditions. Finally, both 3-MA and CQ alleviated, albeit to different degrees, the increased chemoresistance in ANE-s and/or 30-100 K-s cells.
  
  
  CONCLUSIONS
  Chronic stimulations of ANE or ANE 30-100 K may increase tolerance of oral cancer and leukemia T cells to anticancer drugs, as well as to glucose deprivation and hypoxia conditions, and cause an elevation of autophagy activity responsible for increased drug resistance.
authors.affiliation: Department of Dentistry, Taipei Medical University, Taipei, Taiwan; Department of Dentistry, National Defense Medical Center, Taipei, Taiwan; Oral and Maxillofacial Surgery Section, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Yen
authors.forename: Wei-Fan
authors.initials: WF
authors.lastname: Chiang
authors.forename: Shyun-Yeu
authors.initials: SY
authors.lastname: Liu
authors.forename: Pse-Chou
authors.initials: PC
authors.lastname: Cheng
authors.forename: Sheng-Yang
authors.initials: SY
authors.lastname: Lee
authors.forename: Wen-Zhai
authors.initials: WZ
authors.lastname: Hong
authors.forename: Pin-Yen
authors.initials: PY
authors.lastname: Lin
authors.forename: Mei-Huei
authors.initials: MH
authors.lastname: Lin
authors.forename: Young-Chau
authors.initials: YC
authors.lastname: Liu
mesh_terms: D000199:Actins / Q000032:analysis / Q000187:drug effects; D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D001114:Areca; D001343:Autophagy / Q000187:drug effects*; D000071183:Autophagy-Related Proteins; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D002738:Chloroquine / Q000494:pharmacology; D002945:Cisplatin / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000032:analysis / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D005472:Fluorouracil / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007202:Indicators and Reagents; D019169:Jurkat Cells / Q000187:drug effects; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000187:drug effects; D009062:Mouth Neoplasms / Q000473:pathology; D010936:Plant Extracts / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013997:Time Factors
chemical_list: D000199:Actins; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D000071183:Autophagy-Related Proteins; D007202:Indicators and Reagents; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D010936:Plant Extracts; D013778:Tetrazolium Salts; C059087:2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; C025946:3-methyladenine; D002738:Chloroquine; C507524:ATG4B protein, human; D003546:Cysteine Endopeptidases; D005947:Glucose; D000225:Adenine; D002945:Cisplatin; D005472:Fluorouracil
keywords: 5-fluorouracil; areca nut; autophagy; chemoresistance; cisplatin